https://www.amazon.com/BLACK-DECKER-BDCAC202B-Lithium-Charger/dp/B010BFHORK
This will charge a 3 Ah in 1.5 hrs
https://www.amazon.com/dp/B074V7KGVT/ref=emc_b_5_t
This will charge same in about 9 hrs
for 5 Ah in about 3/17 hrs
Wow, what a difference. The battery that came with the (older model ) BLACK+DECKER LSTE523 Li-On String Trimmer trimmer is only good for 15 minutes of constant heavy use, and takes about 3.5 hours to charge, not including the cooling of period before that.
It does not work as well as a plug in or gas one, but it is handy and relatively maintenance free. But it auto feeds more trimmer line when it senses it getting too short, and thus goes thru a lot, it would cost much more if buying the spools B+D (3-Pack $12.79) wants you to, rather than buying 11 refills, 220 ft for $10.15 & FREE Shipping on orders over $25
Thank God for what we can do and help others.